Protective eye masks have long been known for use in a wide variety of activities including, but not limited to, welding, machining, and wood working. Oftentimes, such activities can best be carried out if the equipment operator has not only the necessary eye protection against the potential injury causing aspects of the task, but also a close-up view of the object or objects upon which work is to be undertaken. In the case of welding, a welder may be able to produce a higher quality weld if, during the welding process, the welder has a close range view of a joint at which two or more components are to be welded together. Similarly, a machinist may be able to provide a better machined article by having an enlarged view of the blank to be turned during the machining process. In these and other instances, better visional definition obtained by the operator can result in better visual control over the process, and better control can in turn account for better end results.
In order to achieve the aforedescribed visual capabilities, protective eye masks have been outfitted with optical lenses, frequently embodied in the form of slide-like plates, which can be used either alone or in conjunction with other see-through barriers making up a typical protective eye mask. A conventional technique for determining which one of a number of optical lenses is best suited to provide the required amount of visual acuity for any particular individual involves traditional techniques of vision analysis, which are frequently carried out at a location away from the lens usage site and which very often do not allow for immediate delivery of the lens found to be appropriate. Examples of known devices employed to perform traditional analytical techniques are provided in U.S. Pat. Nos. 4,740,072; 4,452,515 and 4,027,954.
The availability of a simple, low cost apparatus for selecting an optical lens for a protective eye mask, which can be quickly and easily operated by the individual mask wearer at or near the point of mask use and which contains a readily available, immediately usable supply of lenses will have considerable appeal.